The invention relates to an actuating device, especially for use in a throttle device, comprising a turning spindle rotatably mounted in the device housing, the turning spindle being functionally connected via a transmission device with a drive device to displace an actuating element connected with the turning spindle.
In practice such actuating devices are known, for instance, in the fields of maritime or terrestrial oil or gas production. The actuating device is operated either manually or hydraulically. The actuating device varies the passage of a throttle so as to reduce the pressure of, for instance, oil transported from a crude oil source. The oil exits from the crude oil source under a pressure of several hundred bar, and the corresponding throttle device reduces this pressure to less than 100 bar.
In an actuating device known in practice a turning spindle rotatably mounted in the device housing can be displaced in an axial direction by means of a handwheel. The turning spindle is connected with an actuating element which influences the throttling in the throttle device. Normally, a transmission device is disposed between the handwheel and the turning spindle.
Moreover known from practice is an actuating device whereof the turning spindle is adjusted by a hydraulically driven drive device, wherein—in this case—the turning spindle may also be designed as part of piston/cylinder unit in which a piston can be displaced inside a cylinder housing by corresponding hydraulic pressure.
In view of such actuating devices it should be appreciated that the same are arranged in remote and/or difficult to access regions, e.g. below the sea level. A manual actuation, therefore, involves considerable efforts, is cost-intensive and dangerous for the operator. Furthermore, the manual adjustment of the actuating device is hard to cheek, and without enough precision. A hydraulically controlled actuating device requires a plurality of hydraulic lines, corresponding connections, sealing elements, pumps and the like for forming the entire hydraulic system. The work involved is increased with each additional actuating device likewise controlled and operated via the hydraulic system. The work involved is even more increased if the actuating device is located in regions subjected to high pressures, such as below sea level. Such hydraulically controlled and operated actuating devices moreover frequently have to be checked for leakages and the like, within the scope of which the entire hydraulic system including the entirety of supply and discharge pipes, connections, pumps and the like are checked for leakages.
Another drawback of such hydraulic actuating devices resides in that the efforts and the expenses for the exact control of the actuating device are very high.
As far as the manually as well as the hydraulically operated actuating devices are concerned it finally should be noted that the same have to be provided with special safety facilities, for example, for avoiding—in connection with the throttle device—an unintended opening of the throttle and, inter alia, a pressure drop in the hydraulic system. Otherwise, the entire production system could considerably be damaged if the oil, which is subjected to a high pressure, exits without being throttled.